Sometimes SYD airport has a jobsworth just ahead of security weighing the carry-ons, supposed to be 7kg but 8kg seems to pass. Any more than that, they get you to take some stuff out (eg laptop power supply) and put it in your pockets or just carry it as far as security.. where you promptly pack it again. Daft.

Arriving at check-in with an obviously large amount of carry-on and an overweight bag is not recommended. Get a friend to mind your carry-on while you check in, or even leave it in a locker.

Prepare for the worst by packing an overcoat with some of your heavier things in the pockets, so you can take it out to lighten the chceck-in bag if there's talk of a surcharge.